Some colors are more transparent than others. Some colors are very opaque. Test your colors on a separate piece of paper to see how they work together. Too many layers of crayon can make the colors resist each other. This can make it harder to add more color. Use as few colors as possible to get your end result. Scratch out small lines and details (such as hair, the veins in leaves and flowers, etc.) with a craft knife. Crayon is excellent for scratching due to the wax. Do not get frustrated! You will need practice to get the look you want. It's worth it!
Colored Pencils is one of the easiest media to handle since they're pencils and you can control your strokes well. There are also a lot of available colors to choose from. First, cover the entire drawing with light strokes. Then, you can proceed with the thick lines to add texture and effect to your drawing. You can also add some more details in your drawing like this one. Soft pastel was used for the blue shadow_effect.